A streamlined adaptation of John le Carre’s espionage novel featuring veteran spymaster George Smiley, “Tinker Tailor” is definitely, almost defiantly, old school — and, as such, almost revolutionary in its quiet restraint.

That’s right, kids; there’s a different kind of spy life beyond the latest “Mission: Impossible” caper. And your mission, should you choose to accept it, is to settle down, put your brain in gear — and pay attention.

These days, that’s a challenging assignment indeed, especially for short-attention-span moviegoers used to explosive action and adrenaline overload.

Never fear. “Tinker Tailor Soldier Spy” does feature such inevitable espionage-movie ingredients as bloodied bodies that clearly signal to the remaining players that the game is no game at all.

Most of the time, however, things are just as they should be: hush-hush, in both senses of the term.

In contrast to the bombast that dominates most contemporary thrillers, “Tinker Tailor” takes place during the chilly Cold War era of the early ’70s.

With nuclear winter a constant threat, life — at least for the combatants — reflects an appropriately subdued mood.

No wonder George Smiley feels at home.

As portrayed by Gary Oldman with sly, spellbinding inscrutability, Smiley’s hardly the living embodiment of his sunny surname.

Hiding his ever-watchful eyes behind a pair of owlish spectacles, he’s the original see-evil, hear-evil — but speak-no-evil — operative.

That is, until the time comes to reveal what he’s discovered while keeping his mouth shut and his eyes wide open.

After all, what can he say? He’s been drummed out of MI-6, Britain’s secret intelligence service, along with his boss (an appropriately world-weary John Hurt), known to one and all only as “Control.”

Sure, Control’s been acting a bit erratically. Believing there’s a Soviet mole somewhere in the upper echelons of MI-6 (better known to its members as “The Circus”) will do that to you.

And when Control’s attempt to flush out said mole goes scandalously, dangerously awry, both he and his close associate Smiley get put out to pasture.

Yet there’s something about Control’s theory that can’t be so easily dismissed, despite the best efforts of Smiley’s surviving Circus colleagues to prove themselves to the higher-ups.

Some think they protest too loudly — including one buttoned-down bureaucrat (Simon McBurney), who brings Smiley out of retirement to conduct an under-the-radar inquiry to root out the mole lurking somewhere inside the Circus tent, which is populated by such nimble performers as Percy Alleline (a self-righteous Toby Jones), Toby Esterhase (“Girl With the Dragon Tattoo’s” saturnine David Dencik ), Roy Bland (cagey Ciaran Hinds) and Bill Haydon (a blithely dashing Colin Firth), each one more anxious than the next to prove their loyalty.

Little wonder, then, that Smiley doesn’t trust any of them.

Instead, he relies on such out-of-the-mainstream allies as the understandably wary Jim Prideaux (Mark Strong), the rakish Rikki Tarr (“Inception’s” chameleonlike Tom Hardy), forever on the verge of going rogue, and Peter Guillam (“War Horse’s” spit-and-polish Benedict Cumberbatch), who’s still able to slip under the Circus tent when the need arises.

Remember, this is 1973, when spies had to make do with dial telephones, rattling Telex machines and piles of paper files.

Or they could use their imaginations, as Control does, deploying chess pieces to represent the potential suspects as they maneuver for position, power — and the chance to keep playing the game.

This “Tinker Tailor” isn’t the first adaptation of le Carre’s novel; the six-hour 1979 BBC miniseries, with Alec Guinness as Smiley, had more than ample time to follow the tiniest of clues and most Byzantine of plot twists.

Here, screenwriters Peter Straughan (“The Debt”) and Bridget O’Connor (Straughan’s co-writer on the charming “Sixty Six,” who died in 2010) rework and simplify matters to accommodate the movie’s shorter running time. Most of the time, those changes work just fine, although a few emotional glimmers — notably the depth of Smiley’s attachment to his habitually straying spouse — get lost in the shuffle. (This “Tinker Tailor” also reflects a more contemporary Brit-tude when it comes to the Circus performers’ American cousins; as is usual these days, we’re the real bad guys.)

Making an impressive English-language debut, Swedish director Tomas Alfredson (“Let the Right One In”), adopts a quietly methodical pace, one ideally matched to the movie’s melancholy mind games. Occasionally the leaps back and forth in time make it tough to sort out all the pieces on the cinematic chessboard, but that seems less a flaw than a canny reflection of the challenges Smiley faces as he baits and sets his trap en route to the inevitable checkmate.

In recent years, Oldman’s been a stalwart supporting presence as everyone from “Harry Potter’s” Sirius Black to “The Dark Knight’s” Lt. Jim Gordon.

Like Smiley himself, however, Oldman clearly knows how to bide his time.

And now that “Tinker Tailor Soldier Spy” has him back where he belongs — in the center ring — we’re reminded anew of how much power the true masters of the game can generate. Even when they’re balancing on the high wire, seemingly motionless, yet conveying a world of rueful emotion just the same.